Data Security, Data Integrity, Backups & Archives

These are ICT notes from my ICT teacher. GOD BLESS HER!! Thanks to her, i might actually pass GCSE ICT :P:P:P hope these help. i was feeling nice

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  • Created by: mar-rii
  • Created on: 07-06-09 18:54
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Data Security, Data Integrity, Backups & Archiving
Data Security & Data Integrity:
Data security: trying to ensure data is safe
Data security is about keeping data safe from hazards such as: Viruses, Fires, Deliberate Destruction by Hackers,
User Error, and Hardware Failure. Data security includes:
o Keeping backup copies
o Using secure passwords for access to networks, different sections of a network, different folders,
different files
o Encrypting data (encryption means writing a message using a code that is secret except to the
computers sending and receiving the message so that if a hacker accesses the message they won't
understand it)
o Using firewalls
o Regularly checking for viruses using anti-virus software & keeping the anti-virus software up to date
o Logging off computer when you leave it
o Locking a computer when you leave it
o Using physical security, e.g., Locking the Room, Having a Burglar Alarm
Data integrity: trying to ensure data is reliable, in other words that it is accurate
Data integrity is ensuring that data is reasonably accurate and reliable by using verification and validation.
Transcription errors are errors that occur when data is copied from a document into digitally stored data, e.g.,
o You might have written your date of birth on a form as 12/03/1992 and the person typing it into the
computer might type in 03/12/1992,
o You might write your name "Katy" but the person typing it in puts "Katie"
o The person entering your details might put them into the system twice
Verification is used to check the computer version of data matches the original version
For example;
o By looking at the monitor to check it says the same thing as the piece of paper
o By having 2 people entering the same data at the same time & an alarm sounding whenever the data
entered by the 2nd person doesn't match that entered by the 1st person. Both people are typing same
data. If one spells it wrong, then the data isn't the same and so the people are alerted.
Verification is used to check that transcription errors haven't occurred
Verification checks are done when data is 1st entered into a system
Proofreading is a type of verification
Validation checks are carried out by the software to check that data is reasonably accurate
The software usually shows an error message if a validation check finds an error
Validation checks include:
o Format checks e.g. checking an email address has some letters/numbers followed by @ followed by
more letters/numbers
o Presence checks e.g. making sure that something (anything) has been entered into a field on a form
o Range check e.g. checking that data is greater than, less than or between specific boundaries
o Comparison check e.g. checking the data matches a specific list of possibilities such as Mr or Mrs or
Miss
o Check digit check (explained on next page)
When validation rules have been set up they should be tested to make sure they work properly as a validation
rule that doesn't work correctly can cause more problems than not having a validation rule at all. Imagine you set
up a validation rule to only allow numbers bigger than 25 to be entered but by mistake you put <25 instead of
>25 as your validation rule - this mistake would mean that only numbers less than 25 could be entered, in other
words no correct numbers could be entered at all. A common mistake is to forget the = in a validation rule so
instead of putting >=70 (meaning any data entered must be 70 or bigger) you put >70 (meaning any data
entered must be bigger than 70) - the first of these rules would allow 70 to be entered but the 2nd rule
wouldn't.
Validation rules are tested using normal, extreme and abnormal data. Normal data is any data that should be
allowed, Extreme Data is the data at the very edge of what is allowed (the highest and/or lowest values
allowed) and Abnormal Data is data that is not allowed. For example, if the validation rule is >55 Normal Data
would be any number that is allowed such as 70 or 117, etc, Extreme Data is the lowest number allowed which is

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Abnormal Data is any number that is not allowed such as 55
or 40 etc.
Check digit checks use a calculation that adds an extra digit to the end of a number. As long as the computer
receiving the data knows how this extra number has been calculated it can use it to work out if all the other digits
in the number are reasonable - in other words, it uses this extra digit to check the other digits are okay.…read more

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The following diagram shows a bar code. The last digit is used for validation.
a) What is this type of digit called? [1]
Check digit
b) Describe how this digit is used to validate the bar code. [2]
9) A school keeps a database of the names & addresses of its pupils. Each pupil has been asked to write down a
contact telephone number on a form. The school secretary enters the telephone numbers into the database.
The secretary carries out verification of the data.…read more

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Accept
Extreme
Any number
Reject
greater than 6
Abnormal Reject
21) A computer manager is worried about hacking and computer viruses.
a) What is meant by hacking? [2]
b) What is a computer virus? [2]
22) When changing a password why does a user have to type it twice? [1]
23) `Shopping on the Internet is a secure and convenient way to purchase goods.' Discuss this statement. [6]
24) A school must ensure that the data it keeps on staff and pupils is not lost.…read more

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What should the secretary have done before printing out the work to make sure that the two underlined
words were correct? [1]
b) The secretary should have verified the word-processed work. Describe how the secretary could have
verified the work. [2]
32) A school has a large number of computers connected together in a network. A user name and password are
needed to access the computers.…read more

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